Engine Bogs Down Under Load.

Sitherus

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Apr 4, 2016
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I tried moving my needle clip to the first lean spot because it came stock on the second lean spot. it seemed to make no effect.
 


LewieBike

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May 21, 2014
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Put a bigger gear on the crank shifter kit and let that engine rev, you're capping the maximum power by forcing it to lug you and the bike around. With all the mods that engine should be pretty perky once it get into a higher RPM range.

If you don't like the high speed the engine runs at on downhills, pull the clutch in and let it coast. It's easier on the engine and it will give it a cooling cycle and keep enough lubricant present for the idling speed.
 

Sitherus

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Apr 4, 2016
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252
Put a bigger gear on the crank shifter kit and let that engine rev, you're capping the maximum power by forcing it to lug you and the bike around. With all the mods that engine should be pretty perky once it get into a higher RPM range.

If you don't like the high speed the engine runs at on downhills, pull the clutch in and let it coast. It's easier on the engine and it will give it a cooling cycle and keep enough lubricant present for the idling speed.
What do you mean? Which gear? The one on the back of the bike can't be replaced I don't have enough room to put a bigger one on. The lugs for the wheel won't thread on. Or the front one attached to the pedals? We're do I find a bigger one of those. It was hard to get the engine in a place where the chain was the right length to run right. It took me 2 years to figure it out last time. It seems like a big job. I wish three was
Someone local who could look listen and feel and make an informed decision. But every shop won't even let me buy parts ad the moped shops don't like me either because I put an engine on a bike with u bolts.
 

Sitherus

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Apr 4, 2016
Messages
252
Put a bigger gear on the crank shifter kit and let that engine rev, you're capping the maximum power by forcing it to lug you and the bike around. With all the mods that engine should be pretty perky once it get into a higher RPM range.

If you don't like the high speed the engine runs at on downhills, pull the clutch in and let it coast. It's easier on the engine and it will give it a cooling cycle and keep enough lubricant present for the idling speed.
Also there's 2 gears on the front of you mean that one which one?
 

LewieBike

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May 21, 2014
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Also there's 2 gears on the front of you mean that one which one?
In general terms: the higher numerically gearing you can change on your bike like 18:1 > 20:1, the more your engine can rev up.

Since the derailleur drive sprocket on the crank/freewheel is replaceable and the chain is tensioned by the derailleur, I'd try putting a smaller sprocket on. You may have to shorten the chain by a link and readjust your derailleur's upper spring tension screw or "B" screw.

You have a shifter kit on that bike, so you have the ability to allow your engine to rev as high as you need. Kitted and worked on two strokes will generally lose a bit of their broad rpm power for a narrower, more high strung power range or powerband.

These are old school two strokes, they were copied from 1950's Japanese bicycle assist engines that made all of their power across a rather broad rpm range. not much power, but it had a wide RPM band of useable torque.

The only way I could illustrate this is for you to ride an older, dead stock, two stroke Japanese small displacement motorcycle like an old Yamaha, Suzuki, or Hodaka trail bike. These old motorbike's power came on at a few hundred rpm above Idle and extended up into about 6000~9000 rpm.

Your engine is now 'kitted', you took all that useable, lower RPM power and scrunched it up into a narrow 2K to 3K rpm band that comes on with more power, but if you're out of that 'powerband', your engine bogs, doesn't accelerate well and you have to downshift to bring the engine up to revs to keep that power going.

This is really not a great set up for bicycle gearing, which was designed for human leg power that generally can be expected to have a wide range of torque, you can always stand on the pedals a bit to get a little sprint going before you fish for a lower gear to keep from burning up your legs on a climb.

You want that power back? Go back to the stock engine setup.
 
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crassius

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Jul 23, 2012
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also - get a gallon of cheap oil and mix in a can at 4oz to a gallon (shake it really well)
 

Sitherus

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Apr 4, 2016
Messages
252
all that writing and im lost. Do i need to put a bigger gear on the front where the pedals are? or on the back where the wheel is? I cant go stock because I found this engine on the side of the road with no head. this head is the only one I have and the bike has fat wheels so i have to have a jack shaft. I don't feel like offsetting my engine.
 
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